Millions of people across Central America were warned yesterday to brace themselves for further destruction, as the remnants of the record-breaking Hurricane Felix dumped huge quantities of rain over the region, raising the prospect of life-threatening flash floods and landslides.

"Even downgraded to a tropical storm or a tropical depression, it is still very dangerous," senior emergency official Juan José Reyes said in a press conference in the Honduran capital, Tegucigalpa.

Felix has already killed at least four people and left many thousands homeless since smashing into Nicaragua's north-eastern Miskito coast early on Tuesday as a category five storm, the highest on the scale. The victims included a baby born as the storm hit and a woman killed when a falling tree smashed into her home.

A preliminary evaluation of the damage in this poverty-stricken region of remote communities reported 5,500 homes destroyed, many little more than wooden huts. Relatively sturdy buildings also suffered under the howling winds that reached 160mph. The roof was ripped off a church while hundreds of refugees watched from below. Some 90% of the buildings in the fishing town of Puerto Cabezas, the main population centre, reportedly lost their roofs, and many roads were blocked by fallen trees and a spaghetti mesh of cables.

The Nicaraguan government began airlifting mattresses, drinking water and food into the area. President Daniel Ortega also promised to build new and better houses for those left destitute by the hurricane.

Felix was yesterday classified as a tropical depression, after weakening considerably as it moved over northern Nicaragua and into Honduras. It is expected to eventually head south towards El Salvador.

As soon as the storm began to blow itself out, fears shifted from building materials flying through the air to precipitations of as much as 64cm (25in) in some mountain areas. Nine years ago Hurricane Mitch, also downgraded to a tropical storm, stalled over the region for days and dumped huge quantities of water. More than 10,000 people died. Honduran emergency officials said the lessons learned from Mitch of just how dangerous weakening hurricanes can be had aided the evacuation effort.

Some 27,000 Hondurans were waiting out Felix in shelters. Meanwhile, having barrelled in from the Pacific, Hurricane Henriette was yesterday bearing down on north-western Mexico. The category one storm had already passed over the wealthy resorts around Cabo San Lucas on the tip of the Baja California peninsula without causing major damage. From there, it was expected to weaken over Mexico's northern deserts.

Henriette had killed seven people further south along the Pacific coast before it reached hurricane status.

Felix and Henriette were the first hurricanes to strike from the Atlantic and the Pacific on the same day. Felix also set a precedent by hitting land just two weeks after another category five Atlantic storm. Hurricane Dean killed 27 people on its trajectory through the Caribbean and Mexico.

In Mexico Nobel prize-winning scientist Mario Molina and President Felipe Calderón blamed the ferocity of this year's hurricanes on warmer oceans. An expert from the National Hurricane Centre in Miami told the Associated Press that climate change was only a minor factor in overall natural fluctuations.